1. Field of the Invention
This invention relates to a method and apparatus for providing an event forwarding discriminator (EFD) in a computer system. More particularly it relates to providing an EFD that is persistent in its recovery from catastrophic failure of the computing platform on which the EFD is running. Further, the invention provides an EFD that is impervious to invasions from a rogue managing program trying to breach the security of the EFD.
2. Description of Prior Art
Event forwarding discriminators (EFDs) are designed to a Open Systems Interconnection (OSI) standard. An open system is one that may be interconnected with another open system and each system will be compatible with the other. In open systems, EFDs are setup by an OSI managing program running on one computer platform. The manager program manages an agent program running on another computer platform in the same system or an open system connected to the system.
The manager programs and agent programs are application programs that run in association with each other. The manager sends operation request messages to the agent program, and the agent program exercises the resources on behalf of the manager program; the agent sends back event notification messages to the manager.
An EFD monitors event notifications from programs running in its computer system and forwards the notifications of interest to the manager as event reports. The manager program creates the EFDs at the agent program's computer to discriminate as to which notifications are passed back to the manager program. In this way EFDs reduce the communication workload between manager and agent. The manager only sees event reports for those events it has told the agent are significant. All other event reports are discriminated or filtered by an EFD and not passed back to the manager.
The EFD function is described in CCITT Recommendation X.734 entitled "Information Technology--Open Systems Interconnection--Systems Management--Part 5: Event Report Management Function" in ISO/IEC JTC1/SC21 N6360, Aug. 1991. The OSI Manager/Agent functions are described in CCITT Recommendation X.701 entitled "Information Technology--Open Systems Interconnection--Systems Management Overview" in ISO/IEC JTC1/SC21 N6353, Aug. 1991. Templates for the structure of management information are described in CCITT Recommendation X.721 entitled "Information Technology--Open Systems Interconnection--Structure of Management Information--Part 2: Definition of Management Information" in ISO/IEC JTC1/SC21 N-6363, Aug. 1991. Examples of implementation of the OSI Manager/Agent with EFD functions are the IBM Netview programs for the IBM System 390, RISC System 6000 and PS/2 with OS/2.
The advantage of the EFD function is that the manager application program no longer has to poll the managed object programs in the agent application program. Instead the manager sets up EFD program objects to monitor for potential event reports. Potential event reports are derived from notifications emitted by managed objects. When a notification is emitted by a managed object that a manager wishes to see, the EFD can notify the manager by transforming the resulting potential event report into an event report and forwarding it onto the manager.
Some problems exist with current OSI manager/agent structure and the EFDs. First, if the platform on which an EFD is running fails, the EFD can disappear with no notification to the manager. Since the EFD is incapable of forwarding event reports to the manager when the platform goes down, the manager assumes that no events have occurred and does not know the EFD has gone down. Second, EFDs are created, deleted and have attributes specified by a manager. A rogue or illegal manager might delete an EFD created by another manager, or a rogue manager might alter the EFD attributes, such as discrimination criteria or event notification destination list. The legitimate manager has no information about this rogue activity; it may simply just not hear from its EFD again.